This is an area where ALL companies fall short of informing their customers about new channels. My father has Time Warner cable, and while I am a happy Dish customer I find that through forums like these and AVSForums I usually find about about new Time Warner cable channels a long time before he does (unless he accidentally finds them browsing).
I would stumble upon new Dish channels as I check my EPG at least every few days to see what's coming on that I might want to record in the future... but outside of that, this forum is invaluable to me in terms of letting me know what channels to expect and what was just added.
By the time Dish/DirecTV/Cable lets customers know, channels have often been live at least a week or more... some folks haven't noticed new channels for over a month.